Afterburner combustion structure



Nov. 15, 1966 w. HlNES 3,285,002

AFTERBURNER COMBUSTION STRUCTURE 2 Sheets-Sheet 1 Filed Nov. 12, 1964 INVENTOR. EUGENE w. HINES BY MW ATTORNEY Nov. 15, 1966 1-; w, HlNEs 3,285,002

AFTERBURNER comsusnon STRUCTURE Filed Nov. 12, 1964 2 Sheets-Sheet 2 INVENTOR. EUGENE W. HINES ATTORNEY United States Patent 3,285,002 AFTERBURNER COMBUSTION STRUCTURE Eugene W. Hines, 4292 Esta Drive, Flint, Mich. Filed Nov. 12, 1964, Ser. No. 410,505 13 Claims. (CI. 60-30) This invention pertains to an afterburner combustion structure embodied in an internal combustion engine using gasoline or similar hydrocarbon fuels adjacent the exhaust valves of such an engine to substantially further and augment the combustion of unburned fuel in exhaust gases issuing through the valve opening into the head and manifold areas of such an engine.

The invention involves the provision of an insert in the exhaust chamber of the head disposed about the valve stem and relatively closely adjacent the valve behind the valve port for the introduction of additional air to the exhaust gases at their most elevated temperatures in such areas. The gases at such valve ports are still within the temperature range permiting oxidation combustion, and are discharged for emission through eductors secured in the insert, a sup-ply of additional air being furnished by a conduit leading to the inlet of the eductor from a point outside of the manifold. The insert is secured in the cylinder head behind the valve head to channel the exhaust gases containing both burned and unburned fuel at relatively high discharge temperatures into .and through eductors which emit them into the exhaust chambers of the head and manifold. Upon feeding additional air to these gases at such elevated temperatures, a greater amount of or substantially improved combustion of the fuel will ensue within the exhaust chamber of the head and/ or the adjacent manifold chamber.

The motor block cylinder, the cylinder head and the manifold operate substantially as a closed system. A certain amount of air required for combustion of the fuel ignited in the cylinder is provided by the carburetor, but such amount of air, although excellent for admixture purposes to provide a good ignition mixture and a good firing mixture, is substantially insufficient to combust all of the fuel in the cylinder at low or moderate engine speeds. When engine speeds are about 1,000 -r.p.m. or higher, it appears that the air taken in at the carburetor efiiciently combusts substantially most all of the fuel in the cylinder so that a relatively small amount of the exhaust gases contain the undesired unburned hydrocarbons producing smoke and other deleterious discharge from the exhaust system of the engine. But at moderate or -low speeds this is not true, and therefore a quantity of air in addition to that provided by the carburetor is required for more efiicient combustion of the unburned fuel leaving the cylinder at the exhaust valve. Since this added aid cannot be injected directly into the cylinder, it must be provided closely adjacent thereto after discharge of the exhaust gases from the cylinder, the exhaust valve area of the head being the preferred location for such afterburning, since the unburned fuel in these gases is at its highest temperature in such area.

The aforeburning air supply is drawn into the eductors from outside of the manifold, i.e., from outside the confines of the closed system, such air being relatively cool by comparison with the temperatures present in the exhaust chamber and the manifold. The air is also relatively dry and therefore tends to ignite and combust the unburned fuel in the exhaust gases with relative ease. Since the air supply conduit leads directly from outside of the manifold to a point in the eductors where a reduced pressure occurs upon eduction of the exhaust gases, the air supply for afterburning can be provided at atmospheric pressure and without the aid of a pump. This feature of the construction reduces the number of com- 3,285,002 Patented Nov. 15, 1966 ponent parts required, the complexity of the system, and the cost of effecting more efiicient combustion of the unburned fuel issuing from the engine, whose exhaust products, now more fully consumed are discharged from the exhaust end of the engine in a state of substantially reduced hydrocarbon contamination.

It is therefore an object of the invention to provide an afterburner structure in the head of an internal combustion engine which effects a greater and more eflici'ent combustion of the unburned fuel in the exhaust gases issuing from the engine cylinder. It is another object of the invention to provide a relatively simple structure for afterburning of such unburned fuel by means of .an insert in the engine cylinder head having eductors and a conduit leading thereto of an air supply taken from without the engine and open to the atmosphere. A further object is to provide such insert about the valve opening for admission of the air supply to the eductors for combustion of unburned fuel in the exhaust gases when at relatively high temperatures so as to effect further and continued combustion of such unburned fuel in the exhaust chambers of the cylinder head. Yet another object is to provide induction of an air supply to the eductors utilizing the partial vacuum created upon flow of the exhaust gases through the eductors, whereby a reduced pressure or partial vacuum is generated in the air supply conduit. Still a further object is to provide an eductor system with an air supply generated by a reduced pressure or partial vacuum in the air supply conduit, eliminating the necessity of a pump to provide such air supply. Yet another object is to provide valve means in the air supply conduit to prevent discharge of exhaust gases through the air supply conduit when the exhaust valve is closed and greater than atmospheric pressure is present in the exhaust chambers of the head and manifold. A further object is to provide an afterburning device in the cylinder head and manifold structures which is relatively simple, effective and which can be manufactured at relatively low cost.

These and other objects of the invention and features of construction will become more clearly apparent from the description given below, in which the terms employed are used for purposes of description and not of limitation. Reference is made to the drawing annexed hereto and :made an integral part of this specification, in which:

FIGURE 1 is a perspective view of a corner of an engine structure embodying the invention.

FIGURE 2 is a vertical transverse sectional view taken substantially on the line 2-2 of FIGURE 1.

FIGURE 3 is a view similar to FIGURE 2 but showing a modification of the structure illustrated in FIG- URE 2.

FIGURE 4 is a view similar to FIGURE 2 but showing the valve closed in its opening in the head and the air supply conduit closed against emission of exhaust gases.

FIGURE 5 is a substantially plan view, partially in section, taken above the eductors and the air supply conduit leading from the manifold to the afterburning insert, on the line 5-5 of FIGURE 2.

FIGURE 6 is a transverse vertical sectional view of a modification of the structure shown in FIGURE 3.

FIGURES 7 and 8 are substantially horizontal views taken substantially along the lines 7-7 and 8-8 respectively of FIGURE 6.

FIGURE 9 is a fragmentary vertical sectional view showing a slightly modified eductor venturi port.

As shown in the several views of the drawing, the afterburner conbustion structure 10 comprises a shell or dished is designed to fit into the exhaust chamber 22 immediately behind the valve head 24 and closely adjacent the valve seat 26 in the cylinder head, a section 30 of which is pressed into the opening 32 after preparation of the bore '32 in the cylinder head adjacent seat 26 to receive insert 12.

The insert 12 comprises a body 40 having an outer shell or member 42 and an inner shell or member 44 defining a substantially annular air passageway 46 between them, a shoulder 48forming a stop at the outer peripheral edge of the insert where the two shells are integrally conjoined, a valve stem bushing 50 substantially central and axial of the insert and closing the passageway 46 at the valve stem 52, a plurality of eductor openings 54 in the inner shell 44 and a corresponding number of axially aligned eductor openings 56 in the outer shell 42, and an opening 58 in the outer shell 42 for admission of an end of the air supply conduit 16 for communication with the passageway 46.

The insert 12 can be produced as a metal casting, the passageway 46 being cored therein. The configuration of the inner shell or member 44 should be such that the exhaust gases issuing from the cylinder 60 of the engine block 62 under great pressure through the valve port 63 at the seat 26 are channelled directly into the educt-ors 14 to be described more specifically below. The configuration of the outer shell 42 should be such as to leave a clearly defined air passageway 46 between the inner and outer shells as a conduit for air drawn thereinto from the air supply conduit 16.

The eductor 14 can be a modified venturi tube or the two-piece device as illustrated, wherein the inlet member has a tapered Opening 71 therethrough and is disposed in opening 54 of the inner shell 44, and the outlet member 72 is secured in the outer shell 42 in axial alignment with the inlet member 70, a portion of the latter extending into and within the inlet chamber 74 of the outlet member 72. The lead end of the outlet member 72 lies adjacent or within the air passageway 46. Chamber 76 is of generally venturi configuration, -i.e. it has slightly enlarged inlet and outlet openings tapering toward each other and to an intermediate restricted passage or section of smaller diameter than the end openings. The discharge portion of inlet member 70 terminates Within the larger inlet opening 74 of member 72, creating an eductor combination adapted to generate a reduced pressure or partial vacuum at the inlet opening 74 upon throughfiow of gases from member 70 into and through inlet chamber 74 and out of chamber 76 at the discharge end of member 72. A number of such eductors 14 may be used in the insert 12, it being understood that it is desirable to provide a total inlet area for any or all eductors 14 through insert 12 which is substantially equal to the area of the exhaust port 63 through which the exhaust gases flow. By utilizing a plurality of eductors, the ex haust gas pressure in the chamber under shell member 44 should not be materially increased.

The conduit 16 comprises an air supply tube 80 having an air intake or inlet portion 82 disposed exten'orly of the manifold 84 and a portion 87 extending through an opening 86 therein and transversely of the manifold exhaust chamber 88, through the cylinder head exhaust chamber 22 and into opening 58 of the outer shell 42, where the conduit portion 87 terminates at 89 in passageway'46. The end portion 89 is held fixedly secured in the insert member 42 by any suitable means, as by a locking collar 90 threaded into the outer shell 42. Preferably without the manifold 84 and secured to a portion thereof, a reed valve 92 is disposed in the conduit 16 between portions 82 and 87 to provide an automatic means for closing the conduit against emission of exhaust gases, making the conduit 16 a unidirectional passageway for the air supply utilized in the afterburning of unburned fuel in the exhaust gases. The reed valve 92 is of generally conventional construction and can be secured to the manifold 84 or its outer surface in any suitable manner to avoid undesirable nonfunction which may be occasioned by excessive temperatures within the manifold. Optionally, an air filter or cleaner (not shown) can be mounted upon the outboard end 82 of the conduit, or the conduit end 82 can be coupled to another conduit (not shown) leading to the conventional carburetor air cleaner generally mounted close by above the cylinder head.

A modified structure 10 is illustrated inFIGURE 3 in which the valve seat is integrally combined with the insert 12 at the inner shell 44. In this form of the structure the valve seat 26a is provided as a valve insert in the cylinder head wall 94.

The inner shell 44 of the insert 12 can be ribbed (not shown) in the chamber or cavity 96 for channelling the exhaust gases directly to the eductor inlet members 70, or the configuration of the inner shell 44 can be simply dish-shaped as shown. The depth of the cavity 96 is directly relatedto the temperature gradient of the exhaust gases as they pass through and leave the valve seat, and the area and configuration of such chamber should be limited to dimensions wherein the temperature of these gases will support combustion at the eductor outlet member 72 and just beyond such member in the cylinder head chamber 22 upon the admixture of the additional air supply drawn thereinto from the conduit 16.

A further modification of the invention is illustrated in FIGURES 6, 7 and 8. In this form, the structure 10a comprises the insert 100 which is provided preferably with a plurality of eductors 102, although in some instances it is conceivable that a single eductor can be used, an air supply conduit 104 and an air supply cover or manifold 106.

The insert 100 is formed as a casting having a body 107 with venturi chambers or ports 108 spaced substantially about the valve stem bushing 110 with bosses 112 ad jacent the inlet areas 114 of the venturi ports and bosses 116 upon outer surface 118 for the outlet areas 120 of the ports. The latter bosses 116 also provide a shoulder rest for the manifold 106 at the openings 122 therein through which they extend. FIGURE 9 illustrates an eductor having a straight bore venturi port 108 therethrough as a slight modification of the port described above.

The insert body 107 is further provided with air passages 124 and discharge ports 126 as drilled and cored holes, respectively, leading from the outer surface 118 to and through the 114 has a boss 112- in the path or stream of the exhaust gas flow on the downstream side of such flow'into the eductor port 108. It will be noted that such exhaust gas flow washes across the surfaces of the boss in a manner and direction such that a partial vacuum is generated at the surface of the boss containing the air discharge port 126.

The source of air for the eductors 102 is the air supply conduit 104 which is substantially similar to the conduit 16 above described in that it is provided with an intake portion and a reed valve (not shown in the views of FIGURES 6, 7 and 8), a conduit portion or section 130 terminating at 132 within the air space or chamber 134 formed by the insert cover or manifold 106 disposed over and spaced from the outer surface 118 of the insert body 107.

The cover or manifold 10 6 is generally dished to correspond concentrically to the curvature of the surface defined by the planes of rest on bosses 116 at the manifold openings 122, so as to provide the air space or chamber The outer peripheral edges can be inturned as shown, or disposed in any other suitable manner with respect to body 107 to close the air space chamber against any appreciable loss of air passed thereinto by the conduit 104. The edges 140 seat under the body shoulders 142, so that when the body portion 144 is threaded into bosses 112, so that each eductor inlet the cylinder wall 94, the air space 134 is substantially a chamber or passageway through which air is inducted for service of the eductors 102 at air discharge ports 126.

Here again, the total inlet area of all eductor inlets 114 should be substantially equal to the area of the exhaust port 63 between the surface of the valve seat 26a and the complementary valve head surface, to avoid any substantial increase in exhaust gas pressure within the chamber formed by the dished concave surface 150 of the insert body 107 surmounting the valve port 63 and adjacent the valve seat 26a.

In operation, when the engine 20, burning gasoline or similar hydrocarbon fuels, is started and the pistons in their cylinders 60 move under combustion of the intake fuel supply provided thereto, the exhaust gases are discharged from the cylinder by piston ejection into the cylinder head chamber 22. As the valve 24 leaves its seat 26, a passage (port 63) for the exhaust gases containing an undeterminable amount of unburned fuel is provided between the valve seat and the valve head and these gases are forced into the chamber or cavity 96 under the dished inner shell 44 and into the eductor inlet members 70. These gases .are then at very high temperatures and the unburned fuel in such gases at these temperatures is readily combustible upon the admission and admixture of additional oxygen or air therewith. Such air for admixture is pro-vided in the insert passageway 46 when, by throughflow of exhaust gases from eductor inlet member 70 into outlet member 72 a partial vacuum is created at the inlet end 74 of the member 72 and the fresh air supply carried by conduit 16 and the passageway 46 is drawn into the eductor members 72 mixing with the exhaust gases flowing therethrough. Since the partial vacuum at the lead end 74 of the eductor member 72 is less than atmospheric pressure, the reed valve 92 will open to admit air from outside of the manifold. This inflow of a fresh air supply to the eductors 14 continues during the open cycle of the exhaust valve 24, when the exhaust gas pressure is relatively high.

When the valve head 24 closes in its seat 26, a measurable pressure above atmospheric continues in the exhaust chamber 22, the air passageway 46 and the conduit 87, the effect of which is to close the reed valve 92 against further admission of air into conduit 16, maintaining an air supply in the conduit ready for evacuation to the passageway 46 and the eductors 14 upon the next cycle opening of the exhaust valve. Since it is known that the temperature gradiant of the exhaust gases drops off sharply upon leaving the valve opening at seat 26 in conventional cylinder head chambers 22, the insert inner shell 44 should be disposed closely adjacent the valve head and seat. To assist in reducing excessive exhaust gas pressures in the insert chamber 92, a plurality of eductors 14, having a total inlet area subtantially equal to the exhaust gas inlet area at port 63, are recommended for use. A slight restriction of flow of the exhaust gases will, of course, be advantageous in maintaining the gases at temperatures within a combustible range and the dimensional specifications and configuration of the chamber or cavity 96 is predicated upon the determinable physical and thermal characteristics of the exhaust gases taken with the surrounding metal portions of the cylinder head in combination with the insert 12. Once such characteristics have been determined, the specific limits of the insert 12, its shell members 42 and 44 and eductors 14 therein are readily resolved in terms of their configuration and proper engineering design.

Since most cylinder heads 28 are produced as ferrous metal castings, it is preferred to form the insert 12 of the same or similar ferrous metal as a casting in order to reduce as much as possible any undesirable thermal distortions or stresses in actual operation, by maintaining substantially identical thermal coefficients. The air conduit portions 82 and 87 are preferably made of steel tubing. The component elements of eductors 14 are preferably formed and machined of steel but it is also possible that such elements as the members 70 and 72 or suitable modifications thereof can be cast directly into the shells 44 and 42, respectively. The valve stem bushing 50 is preferably formed of bushing material 'well known in the art and adapted to function under the conditions described.

The operation of the modified structure 1011 illustrated in FIGURES 6, 7 and 8 is substantially the'same as for the structure 10 above described. Upon operation of the engine 20, exhaust gases are discharged from cylinder 60 to the cylinder head chamber 22 and through the exhaust port 63 into the cavity or chamber defined by the surface 150. The gases are driven and/ or flow around and across the bosses 112 generating a reduced pressure or partial vacuum at the air discharge ports 126, causing air at atmospheric pressure to be drawn through conduit 104 into the air space 134 and through the passages 124 and .126, into the eductor inlet areas 114 of eductor ports 108, where such oxygen-containing air supply mixes with the unburned fuel of the exhaust gases to ignite and/ or continue combustion of such fuel within the eductors 102, in the cylinder head exhaust chamber 22 and possibly even in the manifold chamber 88, if the thermal conditions and physical relationships of the combustion components support combustion in such latter areas.

Upon closing of the valve head 24 in its seat 26a, the cessation of exhaust gas flow through the eductors 102 permits exhaust gas pressure within the insert chamber 150 and the air in air passages 126, 124, 134 and 130 to increase and close reed valve 92 at the manifold 84, maintaining an air supply in the conduit 104 for the next cycle of exhaust gas discharge from the cylinder 60.

Since combustion of fuel occurs, or is designed to occur at all cylinders of an engine, an insert 12 or should be used at every exhaust port 63 in the cylinder head 28 to reduce the amount of unconsumed hydrocarbons at the tail or discharge end of the exhaust system. Although the inserts 12 and 100 are described and illustrated as being structures that are inserted into the cylinder head 28, it is quite possible that such head can be designed and engineered for fabrication with insert components such as the shells 42 and 44 or the insert body 107 integrally cast into the body portion of the head. In such event, the machined components, surfaces, passages and openings in the inserts above described would be modified or otherwise provided. Such modifications would lie within the skill of persons knowledgeable in the art to which the lnvention pertains.

Having described the invention in its simplest terms, it is to be understood that the features of construction may be changed and varied in greater or lesser degree without departing from the essence of the invention defined in the appended claims.

I claim:

1. In an afterburner structure for an engine having a valved and chambered cylinder head and a communicating exhaust manifold to receive and conduct therethrough quanta of exhaust gases containing unburned fuel as the products and by-products of combustion in said engine,

an insert body in the exhaust chamber of said cylinder heat disposed in relatively adjacent surmounting relationship over and about an exhaust valve port, said insert body having an inner shell defining an exhaust gas receiving chamber over said exhaust valve port and adjacent the valve seat, an outer shell conjoined to said inner shell at their peripheral portions and spaced apart from said inner shell medially to define an air passageway therebetween, at least one exhaust gas eductor disposed transversely of said insert through said inner and outer shells and communicating with said air passageway therebetween, and an opening through said outer shell communicating with said air passageway, and an air supply conduit to serve said eductor having an air discharge portion disposed in said outer shell opening and communicating with said air passageway and an air intake portion disposed outwardly of said manifold. 2. In an afterburner a valved and chambered structure for an engine having cylinder head and a communicating exhaust manifold to receive and conduct therethrough quanta of exhaust gases containing unburned fuel as the products and by-products of combustion in said engine,

a plurality of inserts in said cylinder head,

each said insert having a body in the exhaust chamber of said cylinder head disposed in relatively adjacent surmounting relationship over and about an exhaust valve port,

each said insert body having an inner shell defining an exhaust receiving chamber over said exhaust valve port and adjacent the valve seat, an outer shell conjoined to said inner shell at their peripheral portions and spaced apart from said inner shell medially to define an air passageway therebetween, at least one exhaust gas eductor disposed transversely of said insert through said inner and outer shells and communicating with said air passageway therebetween and an opening through said outer shell communicating with said air passageway, and an air supply conduit to serve each said insert and having a discharge portion disposed in said outer shell opening and communicating with said air pas sageway and an air intake portion disposed outwardly of said manifold.

3. In an afterburner structure for an engine having a valved and chambered cylinder head and a communicating exhaust manifold to receive and conduct therethrough quanta of exhaust fuel as the products and by-products of combustion in said engine,

a body in the exhaust chamber of said cylinder head defining an exhaust gas receiving chamber disposed in relatively adjacent surmounting relationship over and about an exhaust valve port,

said body having members conjoined at their outer peripheral portions and spaced apart medially to define an air passageway therebetween and said exhaust gas receiving chamber over said exhaust valve port and adjacent the valve sea exhaust gas eductors disposed in and transversely through said body and communicating with said exhaust gas receiving chamber, said air passageway and said cylinder head chamber,

and an air supply conduit to serve said eductors having an air intake portion disposed outwardly of said manifold and an air discharge portion communicating with said air passageway in said body.

4. The structure defined in claim 3, wherein the total inlet area of said exhaust gas eductors is substantially equal to the area of said exhaust valve port.

5. In an afterburner structure for an engine having a valved and chambered cylinder head and a communicating exhaust manifold to receive and conduct therethrough quanta of exhaust gases containing unburned fuel as the products and by-products of combustion in said engine,

exhaust gas eduction means in the exhaust chamber of said cylinder head having an insert body disposed in relatively adjacent surmounting relationship over and about an exhaust valve port,

gases containing unburned said insert body having an inner shell defining an exhaust gas receiving chamber over said exhaust valve port and relatively adjacent the valve seat, said insert body having an outer shell spaced apart medially from said inner shell to define an air passageway therebetween, at least one exhaust gas eductor outlet member disposed in said outer shell and communicating with said air passageway and said cylinder head chamber, an eductor inlet member disposed in said inner shell and communicating with said exhaust gas receiving chamber and said eductor outlet member in the area of said air passageway,

a portion of said inlet member being spaced apart from and inwardly of said outlet member, and an air supply conduit to serve said eductor members having an air discharge portion communicating with said air passageway and an air intake portion disposed outwardly of said manifold. 6. The structure defined in claim 5, wherein the inlet area of said exhaust gas eductor inlet member is substantially equal to the area of said exhaust valve port. 7. The structure defined in claim 5, wherein said air supply conduit includes a valve opening upon response of air in said conduit to eduction of said exhaust gases through said eductor outlet element and closing in response to the closing of said valve port. 8. The structure defined in claim 5, wherein the configuration and magnitude of said exhaust gas receiving chamber defined by said inner shell is such as to maintain the unburned fuel in said exhaust gases discharged thereto within the range of combustion at the temperature and pressure present in said eductor outlet member upon admixture of additional air therewith in said latter member. 9. The structure defined in claim 5, wherein a plurality of eductor outlet members and complementary inlet members are disposed in said outer and inner shells respectively. 10. The structure defined in claim 9, the total inlet area of said exhaust members is substantially equal to exhaust valve port. 11. In an afterburner structure for an engine having a valved and chambered cylinder head and a communiwherein gas eductor inlet the area of said through quanta of exhaust gases containing unburned fuel as the products and by-products of combustion in said engine,

exhaust gas eduction means in the exhaust chamber of said cylinder head having an insert body disposed in relatively adjacent surmounting relationship over and about an exhaust valve port,

said insert body defining an exhaust gas receiving chamber over said exhaust valve port and relatively adjacent the valve seat, a plurality of exhaust gas eductors disposed in and transversely through said body, and communicating with said gas receiving chamber and said cylinder head chamber,

a cover for said body overlying and spaced from said body, and having ports therethrough for and about the projecting discharge ends of said eductors, and forming with said body an air passageway therebetween,

passages for air through said body communicating with said air passageway at one end and with discharge ports at their other ends adjacent said eductors and in the flow stream of said exhaust gases thereinto,

projections from said body within said gas receiving chamber in the path of said flow stream into said eductors,

' said projections containing said air discharge ports on the downstream side of said flow stream,

and an air supply conduit to serve said eductors having an air discharge portion terminating at and communicating with said air passageway and an air intake portion disposed outwardly of said manifold.

12. The structure defined in claim 11, wherein the total inlet area of said exhaust gas eductors is substantially equal to the area of said exhaust gas valve port.

13. The structure defined in claim 11, wherein said air supply conduit includes a valve opening upon response of air in said conduit to eduction of said exhaust gases through said eductors and closing in response to the closing of said valve port.

References Cited by the Examiner UNITED STATES PATENTS 2,295,436 9/ 1942 Tendler 60-30 5 2,649,685 8/ 1953 Cohen 6030 3,147,588 9/ 1964 Tausche-k 603O FOREIGN PATENTS 39,448 10/ 1928 Denmark.

10 CARLTON R. C-ROYLE, Primary Examiner.

RALPH D. BLAKESLEE, Examiner. 

1. IN AN AFTERBURNER STRUCTURE FOR AN ENGINE HAVING VALVED AND CHAMBERED CYLINDER HEAD AND A COMMUNICATING EXHAUST MANIFOLD TO RECEIVE AND CONDUCT THERETHROUGH QUANTA OF EXHAUST GASES CONTAINING UNBURNED FUEL AS THE PRODUCTS AND BY-PRODUCTS OF COMBUSTION IN SAID ENGINE, AN INSERT BODY IN THE EXHAUST CHAMBER OF SAID CYLINDER HEAT DISPOSED IN RELATIVELY ADJACENT SURMOUNTING RELATIONSHIP OVER AND ABOUT AN EXHAUST VALVE PORT, SAID INSERT BODY HAVING AN INNER SHELL DEFINING AN EXHAUST GAS RECEIVING CHAMBER OVER SAID EXHAUST VALVE PORT AND ADJACENT THE VALVE SEAT, AN OUTER SHELL CONJOINED TO SAID INNER SHELL AT THEIR PERIPHERAL PORTIONS AND SPACED APART FROM SAID INNER SHELL MEDIALLY TO DEFINE AN AIR PASSAGEWAY THEREBETWEEN, AT LEAST ONE EXHAUST GAS EDUCTOR DISPOSED TRANSVERSELY OF SAID INSERT THROUGH SAID INNER AND OUTER SHELLS AND COMMUNICATING WITH SAID AIR PASSAGEWAY THEREBETWEEN, AND AN OPENING THROUGH SAID OUTER SHELL COMMUNICATING WITH SAID AIR PASSAGEWAY, AND AN AIR SUPPLY CONDUIT TO SERVE SAID EDUCTOR HAVING AN AIR DISCHARGE PORTION DISPOSED IN SAID OUTER SHELL OPENING AN COMMUNICATING WITH SAID AIR PASSAGEWAY AND AN AIR INTAKE PORTION DISPOSED OUTWARDLY OF SAID MANIFOLD. 